Fine-root mortality rates in a temperate forest: estimates using radiocarbon data and numerical modeling
Article first published online: 19 AUG 2009
© LBNL (2009). Journal compilation © New Phytologist (2009)
Volume 184, Issue 2, pages 387–398, October 2009
How to Cite
Riley, W. J., Gaudinski, J. B., Torn, M. S., Joslin, J. D. and Hanson, P. J. (2009), Fine-root mortality rates in a temperate forest: estimates using radiocarbon data and numerical modeling. New Phytologist, 184: 387–398. doi: 10.1111/j.1469-8137.2009.02980.x
- Issue published online: 25 SEP 2009
- Article first published online: 19 AUG 2009
- Received: 23 February 2009Accepted: 8 June 2009
- carbon cycling;
- carbon isotope;
- fine-root turnover time;
- Monte Carlo simulations;
- numerical model;
- root model parameterization;
- • We used an inadvertent whole-ecosystem 14C label at a temperate forest in Oak Ridge, Tennessee, USA to develop a model (Radix1.0) of fine-root dynamics. Radix simulates two live-root pools, two dead-root pools, non-normally distributed root mortality turnover times, a stored carbon (C) pool, and seasonal growth and respiration patterns.
- • We applied Radix to analyze measurements from two root size classes (< 0.5 and 0.5–2.0 mm diameter) and three soil-depth increments (O horizon, 0–15 cm and 30–60 cm).
- • Predicted live-root turnover times were < 1 yr and ∼10 yr for short- and long-lived pools, respectively. Dead-root pools had decomposition turnover times of ∼2 yr and ∼10 yr. Realistic characterization of C flows through fine roots requires a model with two live fine-root populations, two dead fine-root pools, and root respiration. These are the first fine-root turnover time estimates that take into account respiration, storage, seasonal growth patterns, and non-normal turnover time distributions.
- • The presence of a root population with decadal turnover times implies a lower amount of belowground net primary production used to grow fine-root tissue than is currently predicted by models with a single annual turnover pool.